test_serialization failure on ppcl64el and s390x

[detrout]

Hello,

Rebecca Palmer noticed out that test_serialization in partd version 1.2.0's tests occasionally fail on ppc64el and s390x . ( https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1005045 )

=================================== FAILURES 
===================================
______________________________ test_serialization 
______________________________

     def test_serialization():
         with partd_server(hostname='localhost') as (p, server):
             p.append({'x': b'123'})
             q = pickle.loads(pickle.dumps(p))
 >           assert q.get('x') == b'123'
E           AssertionError: assert b'' == b'123'
E             Full diff:
E             - b'123'
E             + b''

test_zmq.py:114: AssertionError

The full logs are at:
https://ci.debian.net/data/autopkgtest/testing/ppc64el/p/partd/18902384/log.gz
https://ci.debian.net/data/autopkgtest/testing/s390x/p/partd/16889914/log.gz

That code failure really looks like some kind of race condition.

We were wondering what to do about this test failure.

Stick a brief sleep in between the append and the get? block building on these architectures? Just ignore it?

Environment:

• Python version: 3.9.10
• Operating System: Debian testing
• Install method (conda, pip, source): Debian package version 1.2.0-1 CI tests.